Exhaust gas purifying thermal reactor

ABSTRACT

A thermal reactor of a three layered type for purifying exhaust gas emitted from an internal combustion engine, which has an inner shell forming a primary reaction chamber therein, an intermediate shell surrounding the inner shell with a secondary reaction chamber formed therebetween and an outer shell or casing surrounding the intermediate shell with an adiabatic space formed between it and the intermediate shell. The inner shell is connected to the intermediate shell at one position intermediate of the length of the inner shell by means of a supporting strip and, similarly, the intermediate shell is connected to the outer shell at one position intermediate of the length of the intermediate shell by means of another supporting strip. Each of these supporting strips is fillet-welded to the adjacent member of these inner, intermediate and outer shells.

United States Patent 11 1 Okitsu et al.

[ Oct. 28, 1975 EXHAUST GAS PURIFYING THERMAL REACTOR [75] Inventors: Kingo Okitsu, Hiroshima; Masashi Shimonaka, Kure, both of Japan [73] Assignee: v Toyo Kogyo Co., Ltd., Japan [22] Filed: Apr. 3, 1974 [21] Appl. No.: 457,560

[30] Foreign Application Priority Data 3,799,196 3/1974 Sheitlin 60/282 Primary ExaminerDouglas Hart Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [57] ABSTRACT A thermal reactor of a three layered type for purifying exhaust gas emitted from an internal combustion en-' gine, which has an inner shell forming a primary reaction chamber therein, an intermediate shell surrounding the inner shell with a secondary reaction chamber formed therebetween and an outer shell or casing surrounding the intermediate shell with an adiabatic space formed between it and the intermediate shell. The inner shell is connected to the intermediate shell at one position intermediate of the length of the inner shell by means of a supporting strip and, similarly, the intermediate shell is connected to the outer shell at one position intermediate of the length of the intermediate shell by means of another supporting strip. Each of these supporting strips is fillet-welded to the adjacent member of these inner, intermediate and outer shells.

4 Claims, 4 Drawing Figures U.S. Patent 0a. 28, 1975 FIG.

FIG. 3

FIG. 2

EXHAUST GAS PURIFYING THERMAL REACTOR The present invention relates to a thermal reactor for purifying exhaust gas emitted from an internal combustion engine and, more particularly, to a thermal reactor of a three chamber type which has an inner shell forming a primary reaction chamber therein, an intermediate shell surrounding the inner shell with a secondary reaction chamber formed therebetween and an outer shell surrounding the intermediate shell with an adiabatic space formed between it and the intermediate shell.

These shells are supported in position by separate supporting strips respectively connecting the inner shell to the intermediate shell within the secondary reaction chamber and the intermediate shell to the outer shell, these connections being made by the employment of a fillet welding method.

A thermal reactor of a similar type, two-chambered though it is, to which the present invention pertains is disclosed in the US. Pat. No. 3,703,083, patented on Nov. 21, 1972, and assigned to the same assignee. According to this US. patent, the reactor generally comprises an inner shell forming a reaction chamber, an outer shell surrounding the inner shell with an adiabatic space formed therebetween, at least one inlet passage through which exhaust gas emerging from the combustion chamber of an internal combustion engine is fed to the reaction chamber, and an exhaust passage through which substantially purified exhaust gas emerging from the reaction chamber is discharged to the atmosphere. Both the inlet and exhaust passages extend through the outer shell and are connected to the inner shell in such a way that either. the inlet passage or the exhaust passage supports the inner shell relative to the outer shell so as to permit the inner shell to move in the axial direction when heat expansion resulting from the heat energy of the elevated temperature that is generated upon combustion within the reaction chamber takes place in the inner shell, while the other supports the inner shell relative to the outer shell so as to permit the inner shell to move in the axial direction and also in the direction substantially orthogonal to the axis of said other passage when the heat expansion takes place in the inner shell.

The reactor of this U.S. patent further comprises a supporting member for fixing the inner and outer shells to each other at a localized area thereby reducing noise and vibration originating from movement of the inner shell. More specifically, the supporting member has one end rigidly secured to the inner shell and the other end connected to the body of the internal combustion engine through a flange used to secure the outer shell to the engine body.

The present invention has an essential object to provide an improved thermal reactor of the threechambered type wherein the inner, intermediate and outer shells are connected to each other by separate supporting strips by the employment of a fillet welding method, with substantial improvement of the durability or service life thereof.

Another object of the present invention is to provide an improved thermal reactor of the type referred to above, which is reliable and efficient for purifying exhaust gas emerging from an internal combustion engine and which can be manufactured without any difficulty and at relatively low costs.

According to a preferred embodiment of the present invention herein disclosed, the thermal reactor comprises an inner shell of a hollow cylinder which forms therein a primary reaction chamberinto which the exhaust gas is introduced. The inner shell is supported in position within an intermediate shell having both ends closed to provide a secondary reaction chamber that is separated from the primary reaction chamber through the wall forming the inner shell. The reaction chamber communicates through the secondary reaction cham' her to an exhaust duct leading to the atmosphere. At a substantially intermediate position of the inner shell, the latter is rigidly connected to the intermediate shell and at another position approximately spaced from the intermediate position about the longitudinal axis of the inner shell the latter is also rigidly connected to the intermediate shell through a supporting strip.

The outer shell is a casing accomodating therein the intermediate shell together with the inner shell and defines, in cooperation with the intermediate shell, the adiabatic space in which heat insulating material such as glass wool is packed. The intermediate shell with the inner shell therein is supported in position within the outer shell through a supporting strip having both ends connected to the outer peripheral surface of the intermediate shell in spaced relation to each other and a substantially intermediate portion thereof spaced from the intermediate shell and connected to the inside surface of the outer shell. The exhaust duct having one end open to the secondary reaction chamber and the other end open to the atmosphere extends through and is supported by the outer shell in such a manner that there is provided a suitable clearance between the exhaust duct and outer shell to permit the exhaust duct to expand without destroying the outer shell.

These and other objects and features of the present invention will become apparent from the following description taken in conjunction with a preferred embodiment thereof with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal section of a thermal reactor embodying the present invention,

FIG. 2 is a cross sectional view taken along the line lIII in FIG. 1,

FIG. 3 is a cross sectional view taken along the line III-Ill in FIG. 1, and

FIG. 4 is a schematic explanatory diagram showing how a fillet welding method employed in the present invention is practised with respect to two metallic elements to be connected together.

Referring now to the accompanying drawings and, particularly, to FIGS. 1 to 3, a thermal reactor embodying the present invention comprises an inner shell 1 of substantially hollow cylindrical shape forming therein a primary reaction chamber A into which exhaust gas of elevated temperature is first introduced from the combustion chamber (not shown) of an internal combustion engine. An intermediate shell 2 having both ends hermetically closed as shown in any suitable manner is greater in size than the inner shell 1 and encloses the inner shell 1 therein, the volumetric difference be tween these shells 1 and 2 providing a secondary reaction chamber B in which portion of unburned compounds of the exhaust gas that has not been sufficiently and completely burned within the primary reaction chamber A is, prior to being discharged to the atmosphere through an exhaust duct 6, subjected to combustion or, if the unburned compounds of the exhaust gas are completely burned within the primary reaction chamber A, through which the substantially purified exhaust gas flows onto the exhaust duct 6 via the secondary reaction chamber B. The intermediate shell 2 with the inner shell 1 therein is enclosed by an outer shell 3 while an adiabatic space C is formed between the intermediate and outer shells 2 and 3. The adiabatic space C may contain therein heat insulating material 13 as shown by broken hatching in FIGS. 2 and 3 which may be glass wool.

Each of the inner and intermediate shells l and 2 is preferably made of an inexpensive ferrous sheet metal of a thickness within the range of from 1.0 to 1.6 mm. and formed into a definite shape as shown by the application of hydraulic pressure or by any other suitable shaping technique, while the outer shell 3 is composed of a pair of cast components 3a and 3b of cast iron, said cast components 3a and 3b being secured together by the use of a plurality of bolts, generally indicated by 30, each firmly tapped through one component 3a or 3b into the other component 3b or 3:1.

As shown, the inner shell 1 contacts the intermediate shell 2 over the entire length thereof and is rigidly connected thereto by means of a circular fillet weld in formed at a position intermediate of the length of either the inner shell 1 or the intermediate shell 2. The inner shell 1 is also connected to the intermediate shell 2 at a position circumferentially spaced approximately 180 from the circular fillet weld m, by means of a supporting strip 4 which is bent or curved to represent a substantially channel-shaped cross section and which has both ends connected to spaced portions of the intermediate shell 2 by means of respective circular fillet weld and p, a substantially intermediate portion of said supporting strip 4 being connected by a circular fillet weld n to that portion of the inner shell 1 circumferentially spaced approximately 180 from the circular fillet weld m.

While the inner shell 1 is supported in position within the intermediate shell 2 in the manner as hereinbefore described, the intermediate shell 2 is supported in position within the outer shell 3 in such a manner as will now be described.

A supporting strip 5 has both ends rigidly connected to spaced portions of the intermediate shell 2 by means of circular fillet welds q and r, a substantially intermediate portion of which extends immediately thereabove and in a spaced relation to the circular fillet weld m on one surface and is, on the other surface, rigidly connected to the cast component 3a of the outer shell 3 by means of a circular fillet weld s. The intermediate shell 2 is also connected to the cast component 3b of the outer shell 3 through the exhaust conduit 6 in a manner as hereinafter described.

The exhaust duct 6 has one end rigidly mounted with a seal ring 7 and the other end rigidly connected to the intermediate shell 2 and opened towards the secondary reaction chamber B in substantial alignment with the circular fillet weld n. The outer shell 3, more specifically, the cast component 3b of said outer shell 3, is formed with an outwardly protruding sleeve portion 3d of a diameter slightly greater than the seal ring 7 on the exhaust duct 6 and also with a radially inwardly extending collar portion 3e of a diameter slightly greater than the outer diameter of the exhaust duct 6. The exhaust duct 6 is supported in position with the seal ring 7 so loosely inserted in the sleeve portion 3d that there is provided a certain clearance between the exhaust duct 6 and outer shell 3 to permit the exhaust duct 6 to expand without destroying the outer shell 3.

In the embodiment as shown, for introducing exhaust gas into the primary reaction chamber A from the internal combustion engine (not shown), a pair of guide tubes, generally indicated by 8, are employed. While one or more than two guide tubes may be employed depending on the number of combustion chambers of the internal combustion engine, the engine chamber displacement and/or other factors known to those skilled in the art, those two guide tube 8 are of the same construction and, therefore, only one of which will now be described for the sake of brevity.

The guide tube 8 has one end closed and the other end formed with a radially outwardly extending flange 8a that is connected to the outer shell 3, more specifically, to the cast component 3b of said outer shell, a substantially intermediate portion 8b of which loosely extends through the inner shell 1 and also through the intermediate shell 2. For avoiding an arbitrary rotation of the guide tube 8 about its own longitudinal axis which may otherwise take place if the flanged end 8a of the guide tube 8 is not rigidly and firmly connected to the outer shell 3, a plurality of elongated pins 9, FIG. 3, may be employed, in which case-each pin 9 should be driven into the outer shell through the flange 8a at that end of the guide tube 8. At this time, the guide tube 8 should be positioned such that a feed opening formed in the guide tube 8 adjacent the closed end thereof faces in a direction remote from the adjacent closed end of the intermediate shell 2 and towards the feed opening 8c of the other guide tube 8.

As best shown in FIG. 3, an annular coupling member 10 of a channel-shaped cross section having an annular groove is axially slidably mounted on the guide tube 8 with said groove thereof firmly receiving therein the intermediate shell 2.

As hereinbefore described, the adiabatic space C may be filled with heat insulating material 13. In the case where the heat insulating material 13 is employed in the form of glass wool, a portion of exhaust gas leaking from the secondary reaction chamber B into the adiabatic space C under pressure through a minute gap between the annular coupling member 10 and the outer periphery of the guide tube 8 will blow the glass wool surrounding the intermediate portion 8b of the guide tube 8 to an extent that fragments of the glass wool are possibly dragged into the secondary reaction chamber B. Although this does not frequently occur, in order to avoid this, a substantially funnel-shaped retaining member 14, in FIG. 3, may be employed to retain and depress a portion of the glass wool around the guide tube 8. As shown in FIG. 2, a similar retaining member 14 may be provided also around the exhaust duct 6.

In the foregoing description, various connections between the inner shell 1, the intermediate shell 2 and the outer shell 3 have been described as made by the individual circular fillet welds m, n, o, p, q, r and s. Each of these circular fillet welds should be understood as formed in such a manner as hereinafter described with reference to FIG. 4.

Assuming that a pair of overlapping plates 1 l and 12 are to be connected, a fillet welding method employed in the practice of the present invention is first carried out by forming a circular opening 11a in the plate 11 prior to the latter being placi ed on the other plate 12 and then performing a fillet welding subject to thecircular opening lla so as to form a circularly welded fil ously been heated to a predetermined temperature in" any known manner, through the guide tubes 8 from the internal combustion engine, are subjected to combustion or rebuming. In most cases, the unburned compounds present in the exhaust gas are completely reburned within the primary reaction chamber and, howi ever, if some of the unburned compounds is left unburned within the primary reaction chamber A, it will be reburned within the secondary reaction chamber B during its flow from the primary reaction chamber A onto the exhaust duct 6 in such a manner as indicated by arrow-headed lines in FIG. 1. This is possible because, at the time the primary reaction chamber A has been heated, the secondary reaction chamber B is also heated and because the temperature of the exhaust gas flowing from the primary reaction chamber A into the secondary reaction chamber B still remains high.

Because of the foregoing arrangement of the thermal reactor according to the present invention wherein the inner, intermediate and outer shells l, 2 and 3 are connected by the use of the supporting strips respectively positioned intermediate of the length of the inner and intermediate shells l and 2 and by the employment of the fillet welding method, heat expansion of the inner and intermediate shells 1 and 2 under the influence of the elevated temperature within the reaction chambers A and B substantially takes place in such a way that portions of the inner and intermediate shells 1 and 2 on both sides of the circular fillet welds, respectively, are lengthwisely extended in the opposite directions with respect to each other. Furthermore, stresses imposed on each circular fillet weld by the elevated temperature and vibrations bothresulting from combustion occurring in the primary and/or secondary reaction chambers A and B are advantageously uniformly distributed in the radial direction.

Moreover, in view of the fact that each circular fillet weld occupies a large space than a spot weld does, a sufficient mechanical strength can be obtained in each circular fillet weld without the latter being easily broken and, therefore, the durability of the thermal reactor constructed according to the present invention can be substantially improved. Employment of relatively thin metallic material for the inner and intermediate shells 1 and 2 is advantageous in that, since the relatively thin metallic material has a relatively small heat capacity, the reaction chambers A and B can be readily heated to a predetermined temperature immediately after the engine has been started. This means that exhaust gas purifying operation commences immediately after the engine starts to operate.

Although the present invention has been fully described by way of the preferred embodiment thereof, it should be noted that various changes and modifications are apparent to those skilled in the art. By way of example, the outer shell 3 may be made of any other suitable metallic material rather than cast iron as hereinabove referred to. Asregards the number of the exhaust ducts 6, it may not be limited to one, but two or more exhaust from.

6 ductscan be advantageously employed..-Furthermore, the outer shell 3 may be provided with apair of inlet and outlet ports oppositely spaced from each other for introducing cooling air and discharging it respectively,

thereby achieving a forced draftcooling of the thermal reactor. In this case, the heat insulating material 13 is not necessary.

Therefore, these changes and-modifications should be construed as included within the true scope of the present invention unless otherwise they depart there- What is claimed is: p I

l. A reactor apparatus for use with an internal combustion engine for purifying the exhaust gases emitted therefrom, said apparatus comprising in combination:

a first reaction chamber comprised of a substantially cylindrical inner shell having both ends open;

a second reaction chamber comprised of an intermediate shell enclosing said inner shell, ends closed and fillet welded to said inner shell at a position intermediate to the length of said inner shell;

an outer shell completely enclosing said intermediate shell and separated therefrom by an adiabatic space therebetween;

at least one pair of guide tubes, each tube having one end operatively connected to the internal combustion engine and the other end extending through said outer shell and said intermediate shell, and into said inner shell, said guide tubes being located on opposite sides of the position at which said inner shell is connected to said intermediate shell and each tube further having in that portion of the tube located in the first reaction chamber an opening in the sidewall thereof opposing the opening in the opposite guide tube;

a first supporting strip having both ends fillet welded to the top portion of said intermediate shell, with the intermediate portion thereof connected to said outer shell by a circular welded fillet at the intermediate portion of the length of said intermediate shell, whereby said intermediate shell is held in position within said outer shell;

a second supporting strip fillet welded at the intermediate position thereof to the inner shell at a position circumferentially from the position where the inner shell is connected to the intermediate shell and with the ends of said second supporting strip fillet welded to the inside of the intermediate shell in a horizontal'plane above the horizontal plane containing the fillet weld connecting the intermediate portion of the strip to the inner shell;

at least one exhaust duct having one end open into the second reaction chamber and the other end directed outwardly and passing through the outer shell for discharging the purified exhaust gas from the apparatus; and

duct support means in the outer shell for supporting the exhaust .duct as it passes therethrough.

2. A reactor apparatus as claimed in claim 1, wherein said adiabatic space between said intermediate and outer shells contains heat insulating material.

3. A reactor apparatus as claimed in claim 2, further comprising retaining means surrounding the inside portion of the outside shell where the guide tubes and the exhaust duct pass through the outside shell for keeping the insulating material spaced from that portion of the around slidably mounted on each of said guide tubes, said groove accommodating therein said intermediate shell at the position whereeach guide tube passes through the intermediate shell. 

1. A reactor apparatus for use with an internal combustion engine for purifying the exhaust gases emitted therefrom, said apparatus comprising in combination: a first reaction chamber comprised of a substantially cylindrical inner shell having both ends open; a second reaction chamber comprised of an intermediate sHell enclosing said inner shell, ends closed and fillet welded to said inner shell at a position intermediate to the length of said inner shell; an outer shell completely enclosing said intermediate shell and separated therefrom by an adiabatic space therebetween; at least one pair of guide tubes, each tube having one end operatively connected to the internal combustion engine and the other end extending through said outer shell and said intermediate shell, and into said inner shell, said guide tubes being located on opposite sides of the position at which said inner shell is connected to said intermediate shell and each tube further having in that portion of the tube located in the first reaction chamber an opening in the sidewall thereof opposing the opening in the opposite guide tube; a first supporting strip having both ends fillet welded to the top portion of said intermediate shell, with the intermediate portion thereof connected to said outer shell by a circular welded fillet at the intermediate portion of the length of said intermediate shell, whereby said intermediate shell is held in position within said outer shell; a second supporting strip fillet welded at the intermediate position thereof to the inner shell at a position 180* circumferentially from the position where the inner shell is connected to the intermediate shell and with the ends of said second supporting strip fillet welded to the inside of the intermediate shell in a horizontal plane above the horizontal plane containing the fillet weld connecting the intermediate portion of the strip to the inner shell; at least one exhaust duct having one end open into the second reaction chamber and the other end directed outwardly and passing through the outer shell for discharging the purified exhaust gas from the apparatus; and duct support means in the outer shell for supporting the exhaust duct as it passes therethrough.
 2. A reactor apparatus as claimed in claim 1, wherein said adiabatic space between said intermediate and outer shells contains heat insulating material.
 3. A reactor apparatus as claimed in claim 2, further comprising retaining means surrounding the inside portion of the outside shell where the guide tubes and the exhaust duct pass through the outside shell for keeping the insulating material spaced from that portion of the intermediate shell where the guide tube and the exhaust duct pass therethrough.
 4. A reactor apparatus as claimed in claim 1, further comprising an annular coupling member having a channel-shaped cross-section and an annular groove therearound slidably mounted on each of said guide tubes, said groove accommodating therein said intermediate shell at the position where each guide tube passes through the intermediate shell. 